35 U.S.C. § 301 — Citation of prior art and written statements

(a) In General — At any time, anyone may cite to the Office, in writing, (1) prior art — patents or printed publications — that they believe bears on whether a claim of a particular patent is valid, or (2) statements the patent owner filed in a proceeding before a federal court or the Office, taking a position on how broad a claim of a particular patent is. (b) Official File — If the person citing the prior art or written statements under subsection (a) explains, in writing, how it applies to at least one claim of the patent, that citation and explanation become part of the patent's official file. (c) Additional Information — A party submitting a written statement under subsection (a)(2) must also include any other documents, pleadings, or evidence from the proceeding where the statement was filed that address that statement. (d) Limitations — A written statement submitted under subsection (a)(2), and any additional information submitted under subsection (c), may only be considered by the Office to determine the proper meaning of a patent claim, and only in a proceeding ordered or instituted under section 304, 314, or 324. If such a statement or information is covered by a protective order, it must be redacted to remove information covered by that order. (e) Confidentiality — If the person citing prior art or written statements under subsection (a) requests it in writing, that person's identity must be excluded from the patent file and kept confidential.